1. Field of the Invention
The invention herein relates to electrical cable, such as television transmission cable, and connectors therefor. More particularly, it pertains to cover devices to protect such connectors from the ambient environment.
2. Description of the Prior Art
Many cable connections are positioned where they are subject to adverse ambient environments, particularly where the connection will be subject to moisture contact from rain, snow or humidity. A typical example a connection for television signal transmission cable, when the cable is attached to a transmission facility outlet, a retransmission station or a subscriber""s connection, such as a residence. Some protection may be afforded by enclosing the connection in a housing, such as the small junction boxes for subscriber hookups commonly seen in residential neighborhoods. However, such housings are not completely weather-tight, and in any event many connections remain in the open, or are located in positions where housings are not practical.
Further, in many cases connections must be made during adverse weather. If, for instance, a cable television circuit or an electric power circuit goes out because of a heavy rainstorm, the immediate demands for restored service by the subscribers require the transmission company to send repair people to make the necessary repairs to the cable as quickly as possible, notwithstanding that the storm may be continuing. Such repairs to a large extent require the installation of new connectors, either for cable splices or for re-connection to transmission or receiving facilities. However, to minimize potential damage to the connectors, their exposure to the elements should be as brief as possible. This requirement for brief exposure (i.e., quick repair) is of course reinforced by the fact that commonly during such a storm there are many service disruptions and the repair people need to spend as little time as possible repairing each individual connection so that they will be able to move quickly to restore service systemwide.
It has been known for some time that it is advantageous to cover such cable connections (whether television transmission cable or other types of electrical cable) to minimize the exposure of the connections to the elements, particularly to moisture. Since the cable segments themselves have moisture impervious coverings throughout their length, the particularly vulnerable portions of a cable system are the individual connectors, which are usually screw-type or soldered metal fittings. Wrapping such connectors with moisture-resistant tape has not proved satisfactory, since the adhesive holding the tape does not adhere well to wet surfaces to start with, and even if initially well-adhered, tends to deteriorate with age and the tape becomes loosened. In addition, tape wrapping is a time consuming procedure and often difficult to do properly in cramped or enclosed locations.
Heat shrinkable tubing has also been used to cover connections. Heat shrinkable tubing is tubing made of thermoplastic polymeric materials which, when subjected to elevated temperatures, shrink and contract around the connection. While such heat shrink tubing has proved more effective than tape wrapping, it still has a number of serious deficiencies. For instance, heat shrinking takes a considerable amount of time for the large diameter, relatively thick wall tubing necessary to use with large diameter cable connectors. Thus, cable installers or repair crews find that while the cable connections themselves may be made quickly, an inordinate amount of time must subsequently be spent slowly shrinking the heat shrink tubing to fit. The shrinking cannot be expedited by applying additional heat. The additional heat will simply char and damage the plastic tubing, rather than appreciably speeding the shrinking process. Further, excessive heat applied to the cable protector will also damage the foam dielectric component of the cable itself. Of course, in many instances, particularly at remote locations, a suitable source of heat is not available to the installation or repair crew. Similarly, in many installations the positioning of the connection is such that even where a heating source is available, the heat cannot be applied evenly to the tubing because the access by the heat source is restricted. Thus, the use of heat shrinkable tubing has had only limited applicability and has been essentially unsuitable where rapid installation or repair is needed to limit the exposure of the connections to the elements.
Protectors using chemical dilation and shrinking have been considered in the past, but have not been practical. The degree of diameter change of which a dilated material is capable is limited, and the variations in diameters of cables and cable connection hardware are greater than the structure of prior art cable protectors utilizing chemical dilation could accommodate.
The present invention overcomes these problems and limitations of the prior art and provides a protective cover for a cable connection or splice which can be easily installed, quickly shrunk into tight vapor resistant protective covering within a matter of a few minutes rather than requiring extended periods of time, and can be installed without the need for any application of heat or use of special tools, equipment or materials. It will be seen that this invention thus is a substantial improvement over the heat shrink products of the past, since the protective device of the present invention shrinks entirely by evaporation of the swelling agent and does not require any effort on the part of the installer, nor the application of any tools or heat sources. The present device is easy to install, merely sliding down the cable once the connection is made, and thus can be satisfactorily installed even in locations where access is difficult (such as a connection being made in a recessed hole) or when inclement weather such as rain would make use of a heating device either awkward or impossible.
The device comprises two interfitting sleeves which are chemically swellable and which are initially in dilated configuration, such that they subsequently shrink into place merely by evaporation of the volatile swelling solvent and cooperatively and synergistically seal the cable connection against exposure to ambient atmospheric conditions, dust, moisture, etc.
In its broadest embodiment, the invention is a protective cover for a cable connector, said connector being affixed to an end of a cable and having an outside diameter greater than an outside diameter of said cable, said cover comprising: an outer elongated annular sleeve formed from a material expandable by contact with an expanding chemical and shrinkable upon removal of said contact with said chemical; an inner elongated annular sleeve formed from a material expandable by contact with an expanding chemical and shrinkable upon removal of said contact with said chemical, said inner elongated annular sleeve disposed within said outer sleeve; said cover with said sleeves in chemically expanded state being moveable into disposition covering said connector and a portion of said cable attached thereto, with said inner sleeve covering at least said portion of said cable but not said connector; whereby when said cover is so disposed over said connector and said portion of said cable and removed from contact with said chemical, said chemical evaporates from said sleeves and said sleeves thereupon shrink to diameters wherein wall thickness of said inner sleeve fills the space between the outside diameters of said connector and said attached portion of said cable sufficiently to permit shrinkage of said outer sleeve to form a tightly fitted and substantially immovable covering secured around said connector and at least a portion of said inner sleeve, thereby preventing said connector from coming into contact with adverse ambient components.
In its configuration as a splice connector, the invention is defined as being for covering the junction between two cables, each cable being attached to a connector with said connectors being interfitting, with the cover further comprising a pair of inner elongated annular sleeve formed from a material expandable by contact with an expanding chemical and shrinkable upon removal of said contact with said chemical, each said inner elongated annular sleeve disposed within said outer sleeve and said inner sleeves being spaced apart and disposed at opposite ends of said outer sleeve; each said inner sleeve in chemically dilated configuration being moveable to cover that portion of a respective one of said cables attached to a respective one of said connectors; and said outer sleeve in chemically dilated configuration with said inner sleeves therewithin being moveable to cover both of said connectors and a portion of each of said inner sleeves when said connectors are interfitted; whereby when said cover is so disposed over said connectors and said portions of said cables and removed from contact with said chemical, said chemical evaporates from said sleeves and said sleeves thereupon shrink to diameters wherein wall thickness of each said inner sleeve fills the space between the outside diameters of said respective connector and said respective attached portion of said cable sufficiently to permit shrinkage of said outer sleeve to form a tightly fitted and substantially immovable covering secured around said connectors and at least a portion of each said inner sleeve, thereby preventing said connectors from coming into contact with ambient moisture.
Both the inner sleeve and the outer sleeve are preferable made of a swellable elastomeric material, preferably a natural or synthetic rubber. Also preferably the inner and outer sleeves will be formed from the same material. Suitable rubbers include EPDM rubber, neoprene or chlorosulfonate polyethylene rubber, of which EPDM rubber is preferred. The rubber can be easily swollen initially by immersing it in any of a variety of known swelling agents, such benzene, toluene or a xylene.